An object of a conventional technology is to avoid accumulation of phase shift on one of a P wiring and an N wiring, by arranging yarn of a glass cloth parallel to an extending direction of wirings so that the yarn intersects the differential wirings in a zig-zag manner, and to therefore prevent generation of skew between the wirings.
Warp yarn 4 and weft yarn 5 constituting glass cloth used for forming a substrate for lamination are arranged so that one or both of the warp yarn 4 and the weft yarn 5 are arranged in a zig-zag manner by a length equal to the total of the widths of differential wirings and the distances between the wirings. Accordingly, the variation in the relative dielectric constant of the substrate for lamination is averaged, thus mitigating the deterioration of waveform quality in differential transmission.
Patent document 1: Japanese Laid-Open Patent Publication No. 2009-73946